[KPhotoAlbum] Database merge script

[Robert Krawitz]

Here's the first cut at my database merge script. It works for both
compressed and uncompressed format on version 7 files.

It takes two arguments: the name of the (first) file whose data you
want to merge into the (second) file, and writes the result to stdout.

Note that there could certainly be features I didn't take into account
because I don't use. The only features I've merged are categories,
images, blocklist, and member groups.

I have read the result into kpa and saved it, and things appear to be
OK :-)